Published research has disclosed that oil-soluble metal compounds can be added to heavy oil to be hydrocracked, to form catalytic particles in situ at hydrocracking conditions.
The most effective metals for this purpose are molybdenum and nickel. Oil-soluble compounds that have been shown to be suitable for this purpose are metal soaps, such as molybdenum naphthenate and nickel di-2-ethylhexanoate.
These metal catalyst precursors can be provided in small concentration, typically 50 to 300 ppm.
At these levels of concentration, the catalyst comes close to being useful on a throw-away basis. This is attractive because there is therefore no need to regenerate the catalyst.
However, the cost of the metal catalyst precursors is sufficiently high so that they have not yet been applied commercially.
There is thus a need to reduce the amount of such metal catalyst precursor required for hydrocracking a given amount of feed oil. It is an object of this invention to achieve that end.
Prior art of interest to the present invention will now be discussed.
U.S. Pat. No. 4,134,825, issued Jan. 16, 1979, to Bearden et al discloses dispersing an oil-soluble catalyst precursor (such as molybdenum naphthenate) in heavy oil and hydrocracking the mixture in a reactor. The patent states that the produced coke in the hydrocracked oil may be separated and recycled to the reactor. It further states that part of the hydrocracking oil (which contains the dissolved residue asphaltene) may also be recycled to the reactor. It will be noted that the patent does not teach separating or isolating the residue asphaltene from the hydrocracked oil.